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| United States Patent |
5,288,575
|
|
Kashizaki
, et al.
|
February 22, 1994
|
Electrophotographic photosensitive member, and electrophotographic
apparatus, device unit and facsimile machine employing the
photosensitive member
Abstract
An electrophotographic photosensitive member has an electroconductive
substrate and a photosensitive layer formed thereon. The photosensitive
layer contains an acetal resin having a component unit represented by the
following formula (1):
##STR1##
wherein X is
##STR2##
R.sub.1 is a substituted or unsubstituted aryl group and a substituted or
unsubstituted heterocyclic group; R.sub.2 is a hydrogen atom and a
substituted or unsubstituted alkyl group; R.sub.3 is a substituted or
unsubstituted alkyl group; A is a substituted or unsubstituted
heterocyclic group and
##STR3##
R.sub.4 is a substituted or unsubstituted heterocyclic group; R.sub.5 is a
hydrogen atom, a substituted or unsubstituted alkyl group, a substituted
or unsubstituted aryl group and a substituted or unsubstituted
heterocyclic group; and n and m are each 0, 1, 2 and 3.
| Inventors:
|
Kashizaki; Yoshio (Kanagawa, JP);
Suzuki; Koichi (Kanagawa, JP);
Go; Shintetsu (Kanagawa, JP);
Sugiyama; Satomi (Kanagawa, JP)
|
| Assignee:
|
Canon Kabushiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
976500 |
| Filed:
|
November 13, 1992 |
Foreign Application Priority Data
| Current U.S. Class: |
430/59.6; 358/296; 399/107; 430/96 |
| Intern'l Class: |
G03G 005/04 |
| Field of Search: |
430/58,59,96
|
References Cited
U.S. Patent Documents
| 3839033 | Oct., 1974 | Matsumo et al. | 96/1.
|
| 5063130 | Nov., 1991 | Kato et al. | 430/96.
|
| Foreign Patent Documents |
| 62-30254 | Feb., 1987 | JP.
| |
| 62-95537 | May., 1987 | JP.
| |
Primary Examiner: Goodrow; John
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper & Scinto
Claims
What is claimed is:
1. An electrophotographic photosensitive member comprising an
electroconductive substrate and a photosensitive layer formed thereon,
said photosensitive layer containing an acetal resin having a component
unit represented by the following formula (1):
##STR19##
wherein X is
##STR20##
R.sub.1 is a substituted or unsubstituted aryl group and a substituted or
unsubstituted heterocyclic group;
R.sub.2 is a hydrogen atom and a substituted or unsubstituted alkyl group;
R.sub.3 is a substituted or unsubstituted alkyl group;
A is a substituted or unsubstituted heterocyclic group and
##STR21##
R.sub.4 is a substituted or unsubstituted heterocyclic group; R.sub.5 is a
hydrogen atom, a substituted or unsubstituted alkyl group, a substituted
or unsubstituted aryl group and a substituted or unsubstituted
heterocyclic group; and
n and m are each 0, 1, 2 and 3.
2. An electrophotographic photosensitive member according to claim 1,
wherein X (1) is:
##STR22##
wherein R.sub.1, R.sub.2, R.sub.3 and n are the same as in formula (1).
3. An electrophotographic photosensitive member according to claim 1,
wherein X (1) is:
##STR23##
wherein A and m are the same as in formula (1).
4. An electrophotographic photosensitive member according to claim 1,
wherein said photosensitive layer has a charge generating layer and a
charge transporting layer.
5. An electrophotographic photosensitive member according to claim 4,
wherein said charge generating layer contains an acetal resin having a
component unit represented by said formula (1).
6. An electrophotographic photosensitive member according to claim 4,
wherein said charge generating layer is disposed on said electroconductive
substrate and said charge transporting layer is disposed on said charge
generating layer.
7. An electrophotographic photosensitive member according to claim 4,
wherein said charge transporting layer is disposed on said
electroconductive substrate and said charge generating layer is disposed
on said charge transporting layer.
8. An electrophotographic photosensitive member according to claim 1,
wherein said photosensitive layer is a single layer.
9. An electrophotographic photosensitive member according to claim 1,
further comprising an undercoating layer between said electroconductive
substrate and said photosensitive layer.
10. An electrophotographic photosensitive member according to claim 1,
further comprising a protective layer overlying said photosensitive layer.
11. An electrophotographic apparatus comprising: an electrophotographic
photosensitive member; electrostatic latent image forming means for
forming an electrostatic latent image on said electrophotographic
photosensitive member; developing means for developing the formed
electrostatic latent image; and transfer means for transferring the
developed image onto a transfer medium,
said electrophotographic photosensitive member comprising an
electroconductive substrate and a photosensitive layer formed thereon,
said photosensitive layer containing an acetal resin having a component
unit represented by the following formula (1):
##STR24##
wherein X is
##STR25##
R.sub.1 is a substituted or unsubstituted aryl group and a substituted or
unsubstituted heterocyclic group;
R.sub.2 is a hydrogen atom and a substituted or unsubstituted alkyl group;
R.sub.3 is a substituted or unsubstituted alkyl group;
A is a substituted or unsubstituted heterocyclic group and
##STR26##
R.sub.4 is a substituted or unsubstituted heterocyclic group; R.sub.5 is a
hydrogen atom, a substituted or unsubstituted alkyl group, a substituted
or unsubstituted aryl group and a substituted or unsubstituted
heterocyclic group; and
n and m are each 0, 1, 2 and 3.
12. A device unit comprising an electrophotographic photosensitive member
and means selected from the group consisting of charging means, developing
means and cleaning means,
said electrophotographic photosensitive member comprising an
electroconductive substrate and a photosensitive layer formed thereon,
said photosensitive layer containing an acetal resin having a component
unit represented by the following formula (1):
##STR27##
wherein X is
##STR28##
R.sub.1 is a substituted or unsubstituted aryl group and a substituted or
unsubstituted heterocyclic group;
R.sub.2 is a hydrogen atom and a substituted or unsubstituted alkyl group;
R.sub.3 is a substituted or unsubstituted alkyl group;
A is a substituted or unsubstituted heterocyclic group and
##STR29##
R.sub.4 is a substituted or unsubstituted heterocyclic group; R.sub.5 is a
hydrogen atom, a substituted or unsubstituted alkyl group, a substituted
or unsubstituted aryl group and a substituted or unsubstituted
heterocyclic group;
n and m are each 0, 1, 2 and 3; and
said electrophotographic photosensitive member and means selected from the
group consisting of charging means, developing means and cleaning means
being assembled together to form said device unit which is detachable from
the main body of an electrophotographic apparatus.
13. A facsimile machine comprising: an electrophotographic apparatus, and
receiving means for receiving image data from a remote terminal,
said electrophotographic apparatus having an electrophotographic
photosensitive member comprising an electroconductive substrate and a
photosensitive layer formed thereon, said photosensitive layer containing
an acetal resin having a component unit represented by the following
formula (1):
##STR30##
wherein X is
##STR31##
R.sub.2 is a substituted or unsubstituted aryl group and a substituted or
unsubstituted heterocyclic group;
R.sub.2 is a hydrogen atom and a substituted or unsubstituted alkyl group;
R.sub.3 is a substituted or unsubstituted alkyl group;
A is a substituted or unsubstituted heterocyclic group and
##STR32##
R.sub.4 is a substituted or unsubstituted heterocyclic group; R.sub.5 is a
hydrogen atom, a substituted or unsubstituted alkyl group, a substituted
or unsubstituted aryl group and a substituted or unsubstituted
heterocyclic group; and
n and m are each 0, 1, 2 and 3.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrophotographic photosensitive
member and, more particularly, to an electrographic layer which contains
an acetal resin having a specific structure. The present invention also
relates to an electrophotographic apparatus, a device unit and a facsimile
machine which employs the electrophotographic photosensitive members.
2. Description of the Related Art
Most known electrophotographic photosensitive members employing organic
photoconductive substances have photosensitive layers formed by dispersing
charge generating substances of relatively low molecular weights, such as
azo pigments or phthalocyuanine pigments, in suitable binder resins. One
kind of organic electrophotographic photosensitive member has a so-called
laminated-type photosensitive layer comprising two layers: a charge
generating layer containing a charge generating substance; and a charge
transporting layer containing a charge transporting substance. Such an
organic electrophotographic photosensitive member exhibits good
sensitivity, potential characteristic and durability, and therefore is
widely used.
In such electrophotographic photosensitive members, the characteristics of
the photosensitive member are substantially determined by factors such as
carrier generating efficiency, carrier transporting efficiency of the
photosensitive layer and further, in the laminated type, the efficiency in
injecting carriers from the charge generating layer into the charge
transporting layer. It is speculated that these factors are affected by
the characteristics of a binder resin as well as the characteristics of
both charge generating substances and charge transporting substances.
However, the primary purpose of the development of the binder resin has
been to improve the binding characteristic, the pigment dispersing
characteristic and the mechanical strength thereof. Although Japanese
Patent Application Laid-Open Nos. 62-30254 and 62-95537 describe that the
structure and molecular weight of the binder resin also affect the
electrophotographic characteristics such as sensitivity, durability or
residual potential of the photosensitive member, they do not clearly
describe that a binder resin can serve as a functional resin, and
satisfactory electrophotographic characteristics have not been achieved so
far.
To meet growing demands for further improving image quality and durability,
an electrophotographic photosensitive member having better
electrophotographic characteristics must be developed.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an
electrophotographic photosensitive member which has a higher sensitivity,
a more stable potential characteristic even after repeated use and,
further, a better residual potential characteristic.
It is another object of the present invention to provide an
electrophotographic apparatus, a device unit and a facsimile machine which
employ the above-mentioned electrophotographic photosensitive members.
To achieve the above objects, the present invention provides an
electrophotographic photosensitive member comprising an electroconductive
substrate and a photosensitive layer formed thereon, said photosensitive
layer containing an acetal resin having a component unit represented by
the following formula (1):
##STR4##
wherein X is
##STR5##
R.sub.1 is a substituted or unsubstituted aryl group and a substituted or
unsubstituted heterocyclic group;
R.sub.2 is a hydrogen atom and a substituted or unsubstituted alkyl group;
R.sub.3 is a substituted or unsubstituted alkyl group;
A is a substituted or unsubstituted heterocyclic group and
##STR6##
R.sub.4 is a substituted or unsubstituted heterocyclic group; R.sub.5 is a
hydrogen atom, a substituted or unsubstituted alkyl group, a substituted
or unsubstituted aryl group and a substituted or unsubstituted
heterocyclic group; and
n and m are each 0, 1, 2 and 3.
Further, the present invention provides an electrophotographic apparatus, a
device unit and a facsimile machine employing the above-described
electrophotographic photosensitive members.
Further objects, features and advantages of the present invention will
become apparent from the following description of the preferred
embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically illustrates the structure of an electrophotographic
apparatus employing an electrophotographic photosensitive member according
to the present invention.
FIG. 2 is a block diagram of a facsimile machine employing an
electrophotographic photosensitive member according to the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An electrophotographic photosensitive member according to the present
invention has a photosensitive layer which contains an acetal resin having
a component unit represented by the following formula (1):
##STR7##
wherein X is
##STR8##
R.sub.1 is a substituted or unsubstituted aryl group and a substituted or
unsubstituted heterocyclic group;
R.sub.2 is a hydrogen atom and a substituted or unsubstituted alkyl group;
R.sub.3 is a substituted or unsubstituted alkyl group;
A is a substituted or unsubstituted heterocyclic group and
##STR9##
R.sub.4 is a substituted or unsubstituted heterocyclic group; R.sub.5 is a
hydrogen atom, a substituted or unsubstituted alkyl group, a substituted
or unsubstituted aryl group and a substituted or unsubstituted
heterocyclic group; and
n and m are each 0, 1, 2 and 3.
More specifically, examples of the aryl group of R.sub.1 are: phenyl,
styryl, biphenyl, 3-naphtyl, anthryl, phenanthryl, etc., and examples of
the heterocyclic group of R.sub.1 are: 2-thienyl, 3-thienyl, 2-furyl,
3-furyl, 2-pyrrolyl, 3-pyrrolyl, 2-pyridyl, 3-pyridyl, 4-pyridyl,
pyridine-4-oxide-4-yl, piperidino, morpholine, etc. Examples of the alkyl
group of R.sub.2 and R.sub.3 are methyl, etc. Examples of the heterocyclic
group of R.sub.4 and A are: 2-thienyl, 3-thienyl, 2-furyl, 3-furyl,
2-pyrrolyl, 3-pyrrolyl, 2-pyridyl, 3-pyrridyl, 4-pyridyl,
pyridine-4-oxide-4-yl, piperidino, morpholine, etc. Examples of the alkyl
group of R.sub.5 are: methyl, ethyl, propyl butyl, etc., and examples of
the aryl group of R.sub.5 are: phenyl, styryl, biphenyl, 3-naphtyl,
anthryl, phenanthryl, etc., and the heterocyclic group of R.sub.5 may be
the same as groups which are allowed for the above groups are: alkyl
groups such as methyl, ethyl and propyl; halogen atoms such as fluorine,
chlorine,, bromine and iodine; acyl groups such as acetyl and benzoyl,
alkoxy groups such as methoxy and ethoxy; aryloxy groups such as phenoxy
and tolyloxy; aralkyl groups such as benzyl and naphtylmethyl; arylalkoxy
groups such as benzyloxy; alkylamino groups such as dimethylamino and
diethylamino; nitro groups; cyano groups; and haloalkyl groups such as
trifluoromethyl.
The weight average molecular weight of acetal resin of the present
invention should preferably be within a range of 10,000 to 1,000,000, and
more preferably, within a range of 100,000 to 500,000. The acetalation
degree thereof should preferably be 30 mol % or greater, and more
preferably, within a range from 50 to 90 mol %. The residue which is not
acetalated may have acetyl groups, propionyl groups, benzoyl groups and
amsylcarbonyl groups, as well as hydroxyl groups. The acetal resin should
preferably be made of polyvinyl alcohol, and the saponification degree
thereof should preferably be 60 mol % or greater, and more preferably, 85%
or greater.
Because the electrophotographic photosensitive member of the present
invention comprises a photosensitive layer containing an acetal resin
having a specific component unit, the sensitivity, the electric potential
stability and residual potential during repeated use are remarkably
improved. It is speculated that these advantages are achieved probably
because electronic interaction between the acetal resin and charge
generating substances improves the carrier generation efficiency and
injection efficiency. More specifically, the electronic interaction
between the acetal resin and charge generating substances promotes
dissociation of carriers and suppresses re-association thereof, thus
working favorably for generation of free carriers.
Preferred examples of the component units of an acetal resin according to
the present invention are presented below. It should be noted, however,
that many other types of component units can also be employed in the
present invention.
##STR10##
An acetal resin employed in the present invention is synthesized by a known
acetalation reaction.
Examples of alcohol ingredients used in this reaction are entirely or
partially-saponified polyvinyl alcohols and copolymers of these alcohols
and various vinyl compounds, and examples of aldehyde ingredients are
corresponding aldehyde and aldehyde acetals, such as dimethylacetal and
diethylacetal.
This acetalation reaction progresses in the presence of acidic catalysts in
an organic solvent containing the above polyvinyl alcohols and either
aldehydes or acetals.
Examples of the organic solvent are: alcohols such as methanol, ethanol,
propanol and 2-methoxyethanol; ethers such as tetrahydrofuran and dioxane;
aromatic hydrocarbons such as toluene, xylene and chlorobenzene;
non-protonic polar solvents such as dimethylsulfoxide, dimethylformamide,
N-methylpyrrolidone, sulfolane and acetonitrile; and esters such as ethyl
acetate, butyl acetate, methyl benzoate and methylcellosolve acetate.
Further, a combination of the above-listed organic solvents or a mixture
of an organic solvent in the above list and water may be used.
Examples of the acidic catalyst are: mineral acids such as hydrochloric
acid and sulfuric acid; sulfonic acids such as p-toluenesulfonic acid and
benzensulfonic acid; zinc chloride; and trifluoroacetic acid. The reaction
temperature should preferably be within a range of 20.degree. to
100.degree. C., and more preferably, within a range of 20.degree. to
60.degree. C.
SYNTHESIS EXAMPLE 1 (SYNTHESIS OF RESIN EXAMPLE 1)
3.5 grams of polyvinyl alcohol (having a polymerization degree of 1,000 and
a saponification degree of 98.5 mol %, made by Kuraray Co., Ltd.) was
suspended in 60 ml of dimethylsulfoxide. 23.2 g of phenylacetone was added
to the suspension, and subsequently, 0.4 g of p-toluenesulfonic acid
monohydride was added. Then, this suspension was heated and stirred at
40.degree. C. for 6 hours. The resultant solution was added in drops to 2
liters of methanol containing 0.1 g of sodium hydroxide, and thereby the
polyvinyl acetal was deposited. The polyvinyl acetal was filtered out and
dissolved into 50 ml of N,N-dimethylformaldehyde. Insoluble materials were
filtered out. The filtrate was added in drops to 2 liters of methanol, and
thereby the polymer was deposited. The polymer was filtered out and then
dried. 4.9 g of the polyvinyl acetal, Resin Example 1, was thus obtained.
The acetalation degree of this polymer was 61.5 mol %, measured by a
method according to Japanese Industrial Standard K6728 (polyvinyl butyral
test method).
SYNTHESIS EXAMPLE 2 (SYNTHESIS OF RESIN EXAMPLE 25)
3.5 g of polyvinyl alcohol (having a polymerization degree of 1,000 and a
saponification degree of 98.5 mol %, made by Kuraray Co., Ltd.) was
suspended in 60 ml of dimethylsulfoxide. 17.8 g of 2-thiophenaldehyde was
added to the suspension, and subsequently, 0.4 g of p-toluenesulfonic acid
monohydrate was added. Then, this suspension was heated and stirred at
40.degree. C. for 6 hours. The resultant solution was added in drops to 2
liters of methanol containing 0.1 g of sodium hydroxide, and thereby the
polyvinyl acetal was deposited. The polyvinyl acetal was filtered out and
dissolved into 50 ml of tetrahydrofuran. Insoluble materials were filtered
out. The filtrate was added in drops to 2 liters of methanol, and thereby
the polymer was deposited. The polymer was filtered out and then dried.
5.8 g of the polyvinyl acetal, Resin Example 25, was thus obtained. The
acetalation degree of this polymer was 70 mol %, measured by a method
according to Japanese Industrial Standard K6728 (polyvinyl butyral test
method).
The photosensitive layer of the electrophotographic photosensitive member
of the present invention may be either a laminated type which is composed
of functionally different layers: a charge generating layer containing a
charge generating substance; and a charge transporting layer containing a
charge transporting substance, or a monolayer type which is composed of a
single layer containing a charge generating substance and a charge
transporting substance. However, a laminated type photosensitive layer is
more preferably. In the case of the laminated type, the above-described
polyvinyl acetal should preferably be contained in the charge generating
layer.
According to the present invention, the photosensitive layer should
preferably contain the above-described polyvinyl acetal 10 to 90%, and
more preferably, 20 to 50%, by weight with respect to the total weight of
the layer containing the polyvinyl acetal.
An acetal resin according to the present invention may used together with
other polymers. Examples of the other polymers are: resins such as
polyvinyl butyral, polyvinyl benzal, polyarylate, polycarbonate,
polyester, phenoxy resin, acrylic resin, polyacrylamide, polyamide,
polyurethane, polystyrene and acrylonitrile-styrene copolymer; and organic
photoconductive polymers such as poly-N-vinylcarbazole or polyvinyl
anthracene.
Examples of the charge generating substances are: azo-type pigments such as
mono azo, bis-azo and tri-azo; phthalocyanine-type pigments such as metal
phthalocyanine and metal-free phthalocyanine; indigo-type pigments such as
indigo and thioindigo; polycyclic quinone-type pigments such as
anthanthrone and pyrenequinone; perylene-type pigments such as perylenic
acid anhydride and perylenic acid imide; squarilium-type dye; pyrylium;
thiapyrylium; and triphenylmethane-type pigments.
Charge transporting substances fall into two groups: electron transporting
substances, and positive hole transporting substances. According to the
present invention, examples of the electron transporting substances are
electron receiving substances, such as 2,4,7-trinitrofluorene,
2,4,5,7-tetranitrofluorene, chloranil and tetracyanoquinodimethane, and
high molecular substances having these electron receiving substances as
their components. Examples of the positive hole transporting substances
are: polycyclic aromatic compounds such as pyrene and anthracene;
heterocyclic compounds such as compounds of carbazole, indole, imidazole,
oxazole, thiazole, oxadiazole, pyrazole, pyrazoline, thiadiazole and
triazole; hydrazone compounds such as
p-diethylaminobenzaldehyde-N,N-diphenylhydrazone, and
N,N-diphenylhydrazino-3-methylidene-9-ethyl carbazole; styryl compounds
such as .alpha.-phenyl-4'-N,N-diphenylaminostilbene and
5-[4-(di-p-tolylamino) benzylidene]-5H-dibenzo [a,d] cycloheptene;
benzidine compounds; triarylmethane compounds; triphenylamine compounds;
and polymers, such as poly-N-vinylcarbazole or polyvinylanthracene, having
a group composed of an above-listed compound in the main or side chains.
When the charge transporting substance itself does not have any
film-forming nature, the charge transporting layer can be formed with the
aid of a binder resin. More specifically, it is possible to use an
insulating resin such as an acrylic resin, polyarylate, polyester,
polycarbonate, polystyrene, acrylonitrile-styrene copolymer,
polyacrylamide, polyamide or chlorinated rubber, as well as an organic
photoconductive polymer such as poly-N-vinylcarbazole and polyvinyl
anthracene.
Examples of the solvent which is used to form a photosensitive layer
containing an acetal resin according to the present invention are: ethers
such as tetrahydrofuran and 1,4-dioxane; ketones such as cyclohexanone,
methylethylketone and 2-methoxy-2-methyl-4-pentanone; amides such as
N,N-dimethylformamide; esters such as ethyl acetate and butyl acetate;
aromatic compounds such as toluene, xylene and chlorobenzene; alcohols
such as methanol and ethanol; and aliphatic hydrocarbon halides such a
methylene chloride.
The charge generating layer of a laminated-type photosensitive layer should
preferably have a thickness of 5 .mu.m or less, and more preferably,
within a range of 0.01 to 1 .mu.m. The charge transporting layer is
laminated on top of or under the charge generating layer. The thickness of
the charge transporting layer should preferably be within a range of 5 to
40 .mu.m, and more preferably, within a range of 15 to 30 .mu.m. A
monolayer-type photosensitive layer should preferably have a thickness
within a range of 1 to 40 .mu.m, and more preferably, within a range of 10
to 30 .mu.m.
Examples of a material for an electroconductive substrate according to the
present invention are: aluminum, an aluminum alloy, copper, zinc,
stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium,
gold and platinum. The electroconductive substrate also may be formed by
plastic (e.g., polyethylene, polypropylene, polyvinyl chloride,
polyethylene terephthalate or an acrylic resin) coated with any one of the
above-listed metals or alloy by vacuum deposition, a plastic or metallic
plate coated with conductive particles (e.g., carbon black or silver
particles) and a suitable binder resin. Still further, the conductive
particles may be held in a plastic or paper material to form the
substrate.
The electroconductive substrate should be in the shape which is most
suitable to the electrophotographic apparatus which employs the
photosensitive member, for example, the shape of a drum, sheet or belt.
According to the present invention, an undercoating layer which serves as a
barrier and an adhesive may be formed between the electroconductive
substrate and the photosensitive layer. The undercoating layer may be
formed of any of the following: casein, polyvinyl alcohol, nitrocellulose,
polyamides (nylon 6, nylon 66, nylon 610, copolymerized nylon or nylon
alkoxymethylate), polyurethane or aluminum oxide. The thickness of the
undercoating layer should preferably be 5 .mu.m or less, and more
preferably, within a range of 0.1 to 3 .mu.m.
Further, according to the present invention, a resin layer or a resin layer
containing conductive particles may be laminated on top of the
photosensitive layer for protection thereof.
The above-described layers may be formed by a desired application method
such as dip coating, spinner coating, bead coating, blade coating, spray
coating or beam coating.
The electrophotographic photosensitive member of the present invention can
be applied to not only electrophotographic copying machines but also a
wide variety of other electrophotographic equipment such as laser
printers, CRT printers, LED printers, liquid crystal printers, laser plate
making systems or facsimiles.
FIG. 1 schematically illustrates the structure of an embodiment of the
electrophotographic apparatus of the present invention which employs an
electrophotographic photosensitive member of the present invention.
Referring to FIG. 1, a drum-shape photosensitive member 1 for carrying an
image is rotated about a shaft 1a in the direction of an arrow at a
predetermined rotational speed. While the photosensitive member 1 is
rotating, the peripheral surface of the photosensitive member 1 is
uniformly charged with a predetermined level of positive or negative
electric potential by charging means 2 and subsequently subjected to image
light exposure L (e.g., slit light exposure or laser beam scanning
exposure) at an exposure region 3 by exposure means (not shown). Thus, an
electrostatic latent image is continuously formed on the peripheral
surface of the photosensitive member 1, corresponding to the exposure
image.
The thus-formed electrostatic latent image is toner-developed by developing
means 4. The toner-developed image is subsequently transferred by
transferring means 5 onto a transfer material P, which is fed from a
feeding unit (not shown) into a gap between the photosensitive member 1
and the transferring means 5 synchronously with rotation of the
photosensitive member 1.
After receiving the transferred image, the transfer material P is separated
from the surface of the photosensitive member 1 and led to image fixing
means 8, which then fixes the image. Then, the transfer material P is
discharged, carrying a copy image thereon.
After the image transfer, the surface of the photosensitive member 1 is
cleaned by cleaning means 6, which removes remaining toner from the
surface. Then, the surface is discharged by pre-exposure treatment means
7. The photosensitive member 1 is thus repeatedly used for image forming.
One of the most widely-used charging means 2 for uniformly charging the
photosensitive member 1 is a corona electrical charging device. One of the
most widely-used transferring means 5 is a corona electrical transferring
device. According to the present invention, two or more component units of
the above-described photosensitive member, developing means, cleaning
means, etc., may be assembled into a device unit which is detachable from
the main body of the apparatus. For example, a photosensitive member is
combined with at least one of charging means, developing means or cleaning
means to form a device unit separate from the apparatus main body, and
guide means, such as a rail in the main body, is provided for detachably
incorporating the device unit into the main body. The device unit may
further comprise charging means and/or developing means.
In the case where the electrophotographic apparatus of the present
invention is used as a copying machine or a printer, light image exposure
L is performed by irradiating the photosensitive member with light
reflected from or transmitted through an original image, or by irradiating
the photosensitive member by means of laser beam scanning, LED array
driving or liquid crystal shutter array driving in accordance with signals
from a sensor which reads an original image.
In the case where the electrophotographic apparatus of the present
invention is used as the printer of a facsimile machine, light image
exposure L is performed in order to print according to data received form
the outside. FIG. 2 is a block diagram of such a facsimile machine.
Referring to FIG. 2, a controller 11 controls an image reading part 10 and
a printer 19. The entire system of the controller 11 is controlled by a
CPU 17. Data read by the image reading part 10 is transmitted through a
transmitting circuit 13 to a communication partner apparatus. Data
received from a communication partner apparatus is sent through a
receiving circuit 12 to the printer 19. An image memory 16 stores
designated image data. A printer controller 18 controls the printer 19.
Reference numeral 14 denotes a telephone.
Image received through a line 15 (or image data received from a remote
terminal connected to the other end of the line 15) is demodulated by the
receiving circuit 12, decoded by the CPU 17 and then sequentially stored
in the image memory 16. When at least one page of decoded image data is
stored in the memory 16, the image data of the page is printed as follows.
The CPU 17 reads out the decoded image data of the page from the memory 16
and sends the decoded image data to the printer controller 18. When
receiving the image data of the page from the CPU 17, the printer
controller 18 controls the printer 19 so that the printer prints out the
image of the page.
While the printer 19 is performing printing, the CPU 17 receives image data
of the next page.
The facsimile thus receives image data and prints out the image.
EXAMPLE 1
5 g of nylon methoxymethylate (number average molecular weight of 32,000)
and 10 g of alcohol-soluble copolymerized nylon (number average molecular
weight of 29,000) were dissolved into 95 g of methanol. The obtained
solution was applied to an aluminum substrate by using a wire bar and then
dried. An undercoating layer having a thickness of 1 .mu.m was thus
formed.
90 g of cyclohexanone was added to 5 g of bis-azo pigment represented by
the following formula:
##STR11##
The pigment was dispersed in cyclohexanone for 20 hours by a sand mill.
Then, a solution prepared by dissolving 2.5 g of polyvinyl acetal of Resin
Example 1 into 20 g of cyclohexanone was added to the pigment-dispersed
solution. The mixture was further dispersed for 2 hours. The resulting
dispersed solution was diluted by adding 200 g of methylethylketone. The
diluted solution was applied onto the undercoating layer to a thickness of
0.2 .mu.m by using a wire bar, thus forming a charge generating layer.
Next, 5 g of a triarylamine compound represented by the following formula:
##STR12##
and 5 g of polycarbonate (number average molecular weight of 55,000) were
dissolved into 40 g of chlorobenzene. The obtained solution was applied
onto the charge generating layer by using a wire bar so as to form a
charge transporting layer having a thickness of 20 .mu.m.
For evaluation of the charging characteristic of the thus-produced
electrophotographic photosensitive member, the member was negatively
charged by corona discharging of -5 KV by using an electrostatic copying
paper testing apparatus Model SP-428 made by Kawaguchi Kabushiki Kaisha,
let to stand for one second in a dark place and then exposed to an
illumination intensity of 10 lux by using a halogen lamp. A surface
potential (V.sub.O), an exposure (E1/2) required to attenuate the surface
potential after standing for one second (dark potential: V.sub.D) to 1/2
and a residual potential (V.sub.r) were measured to evaluate the charging
characteristics of the member.
The results are shown in Table 1.
EXAMPLES 2 TO 5
Electrophotographic photosensitive members were produced and evaluated by
the same manner as those in Example 1, except that the pigments shown in
Table 1 were used.
The results are shown in Table 1.
EXAMPLES 6 TO 10
Electrophotographic photosensitive members were produced in the same manner
as those in Example 1, except that the acetal resin shown in Table 1 was
used, that tetrahydrofuran was used instead of cyclohexanone, and that a
1:1 (by weight) mixture solvent of tetrahydrofuran and cyclohexanone was
used instead of methylethylketone. The obtained photosensitive members
were evaluated in the same manners as those in Example 1.
The results are shown in Table 1.
TABLE 1
______________________________________
Resin V.sub.o E1/2 V.sub.r
Example Example (-V) (lux .multidot. sec)
(-V)
______________________________________
1 1 707 1.11 0
2 4 705 1.05 0
3 6 703 1.13 0
4 8 700 1.25 0
5 24 701 1.32 0
6 25 708 1.38 0
7 26 710 1.34 0
8 28 710 1.00 0
9 39 703 1.28 0
10 52 702 1.03 0
______________________________________
EXAMPLE 11
An electrophotographic photosensitive member was produced in the same
manner as those in Example 1, except that the polyvinyl acetal of Resin
Example 4 and a bis-azo pigment represented by the following formula:
##STR13##
were used instead. The charging characteristic of the obtained
photosensitive member was evaluated in the same manner as those in the
above examples.
The results were as follows: V.sub.O, -700 V; E1/2, 1.39 lux.multidot.sec;
and V.sub.r 0 V.
EXAMPLE 12
An electrophotographic photosensitive member was produced in the same
manner as those in Example 6, except that the polyvinyl acetal of Resin
Example 28 and the same bis-azo pigment as used in Example 11 were used
instead. The charging characteristic of the obtained photosensitive member
was evaluated in the same manner as in the above examples.
The results were as follows: V.sub.O, -700 V; E1/2, 1.56 lux.multidot.sec;
and V.sub.r, 0 V.
EXAMPLE 13
An electrophotographic photosensitive member was produced in the same
manner as those n Example 1, except that cyclohexanone as a dispersion
solvent was used, that methylethylketone as a dilution solvent was used,
that a bis-azo pigment represented by the following formula:
##STR14##
was used and that a styryl compound represented by the following formula:
##STR15##
was used instead of the triarylamine compound as a charge transporting
substance. The charging characteristic of the obtained photosensitive
member was evaluated in the same manner as those in the above examples.
The results were as follows: V.sub.O, -700 V; E1/2, 1.01 lux.multidot.sec;
and V.sub.r, 0 V.
EXAMPLE 14
An electrophotographic photosensitive member was produced in the same
manner as those in Example 6, except that the same bis-azo pigment,
dispersion solvent and charge transporting substance as used in Example 13
were used instead. The charging characteristic of the obtained
photosensitive member was evaluated in the same manner as those in the
above examples.
The results were as follows: V.sub.O, -700 V; E1/2, 1.95 lux.multidot.sec;
and V.sub.r, 0 V.
EXAMPLE 15
An electrophotographic photosensitive member was produced in the same
manner as those in Example 1, except that a dispersion solution, prepared
by adding 350 g of tetrahydrofuran to 10 g of a metal-free phthalocyanine,
mixing the obtained solution with a solution prepared by dissolving 5 g of
the polyvinyl acetal of Resin Example 4 into 50 g of tetrahydrofuran, and
dispersing the mixture by using a sand mill for 10 hours, was used instead
in order to form a charge generating layer. The charging characteristic of
the obtained photosensitive member was evaluated in the same manner as
those in the above examples.
The results were as follows: V.sub.O, -700 V; E1/2, 1.23 lux.multidot.sec;
and V.sub.r, -15 V.
EXAMPLE 16
An electrophotographic photosensitive member was produced in the same
manner as those in Example 15, except that the polyvinyl acetal of Resin
Example 28 was used instead. The charging characteristic of the obtained
photosensitive member was evaluated in the same manner as those in the
above examples.
The results were as follows: V.sub.O, -700 V; E1/2, 1.13 lux.multidot.sec;
and V.sub.r, -5 V.
EXAMPLE 17
An electrophotographic photosensitive member was produced in the same
manner as those in Example 15, except that copper phthalocyanine was used
instead of the metal-free phthalocyanine. The charging characteristic of
the obtained photosensitive member was evaluated in the same manner as
those in the above examples.
The results were as follows: V.sub.O, -700 V; E1/2, 1.28 lux.multidot.sec;
and V.sub.r, -10 V.
EXAMPLE 18
An electrophotographic photosensitive member was produced in the same
manner as those in Example 16, except that copper phthalocyanine was used
instead of the metal-free phthalocyanine. The charging characteristic of
the obtained photosensitive member was evaluated in the same manner as
those in the above examples.
The results were as follows: V.sub.O, -700 V; E1/2, 1.35 lux.multidot.sec;
and V.sub.r, -5 V.
COMPARATIVE EXAMPLES 1, 2 AND 3
Electrophotographic photosensitive members were produced in the same manner
as those in Example 1, except that polyvinyl acetals (acetalation degrees
of 75 to 80 mol %) having structures as shown in Table 2 was used instead
of the polyvinyl acetal of Resin Example 1. The charging characteristic of
the obtained photosensitive member was evaluated by the same method as in
the above examples.
The results are shown in Table 2.
TABLE 2
______________________________________
Structure V.sub.o E1/2 V.sub.r
of Resin (-V) (lux .multidot. sec)
(-V)
______________________________________
Com- parative Example 1
##STR16## 695 2.95 5
Com- parative Example 2
##STR17## 710 3.25 5
Com- parative Example 3
##STR18## 700 1.90 10
______________________________________
EXAMPLE 19
An electrophotographic photosensitive member was produced as follows: 4 g
of the bis-azo pigment as used in Example 1 was added with 90 g of
cyclohexanone and dispersed for 20 hours by a sand mill. The dispersed
solution was added with a solution prepared by dissolving 20 g of the
polyvinyl acetal of Resin Example 4 into 300 g of tetrahydrofuran, and
shaken for 2 hours. The solution was then mixed with a solution prepared
by dissolving 40 g of the triarylamine compound as used in Example 1 and
20 g of the polyvinyl acetal of Resin Example 4 into 200 g of
tetrahydrofuran, and the mixture was again shaken. The thus prepared
solution was applied to an aluminum substrate by using a wire bar so as to
form a photosensitive layer having a thickness of 20 .mu.m, thus obtaining
an electrophotographic photosensitive member. The charging characteristic
of this electrophotographic photosensitive member was evaluated in the
same manner in Example 1, except that the member was positively charged
and that no residual potential V.sub.r was measured in Example 19.
The results were as follows: +675 V; and E1/2, 2.53 lux.multidot.sec.
EXAMPLE 20
An electrophotographic photosensitive member was produced in the same
manner as those in Example 19, except that the polyvinyl acetal of Resin
Example 25 was used instead. The charging characteristic of the obtained
photosensitive member was evaluated in the same manner as those in Example
19.
The results were as follows: V.sub.O, +650 v; and E1/2, 2.31
lux.multidot.sec.
EXAMPLES 21 TO 26
The electrophotographic photosensitive members produced in Examples 2, 4,
5, 7, 8 and 9 were attached to cylinders of electrophotographic copying
machines each comprising: a corona charging unit of -6.5 KV, an exposure
optical system, a developing unit, a transfer charging unit, a discharging
exposure optical system, and a cleaner. The initial levels of the dark
potential V.sub.D and the light potential V.sub.L were set at about -700 V
and -200 V, respectively. The initial potentials V.sub.D, V.sub.L and the
potentials V.sub.D, V.sub.L after being repeatedly used 5,000 times were
measured. The amount of variation in the dark potential (.DELTA.V.sub.D)
and the amount of variation in the light potential (.DELTA.V.sub.L) were
obtained to evaluate the durability characteristics of the photosensitive
members.
The results are shown in Table 3. In Table 3, the negative values of the
amount of potential variation mean that the absolute values of potentials
decreased, and the positive values thereof mean that the absolute values
of potentials increased.
COMPARATIVE EXAMPLES 4, 5 AND 6
The durability characteristics of the electrophotographic photosensitive
members produced in Comparative Examples 1, 2 and 3 were evaluated in the
same manner as those in Example 21.
The results are shown in Table 3. T1 TABLE 3-.DELTA.V.sub.D (V)?
.DELTA.V.sub.L (V)? -Example ? ? -21 0 +5 ? -22 +5 0 -23 0 +10 ? -24 -5
0 -25 +5 0 -26 0 0 -Comparative Example -4 -30 ? +20 ? -5 -20 ? +25 ?
-6 -50 ? +20 ? -
EXAMPLE 27
An electrophotographic photosensitive member was produced in the same
manner as those in Example 2, except that a charge generating layer was
disposed on a charge transporting layer. The charging characteristic of
the obtained photosensitive member was evaluated in the same manners as
those in Example 1, except that the member was positively charged and no
residual potential V.sub.r was measured.
The results were as follows: V.sub.O, +700 V; and E1/2, 1.85
lux.multidot.sec.
EXAMPLE 28
An electrophotographic photosensitive member was produced in the same
manner as those in Example 6, except that a charge generating layer was
disposed on a charge transporting layer. The charging characteristic of
the obtained photosensitive member was evaluated in the same manner as
those in Example 1, except that the member was positively charged and that
no residual potential V.sub.r was measured.
The results were as follows: V.sub.O, +710 V; and E1/2, 1.78
lux.multidot.sec.
EXAMPLE 29
An electrophotographic photosensitive member was produced in the same
manner as those in Example 1, except that a solution prepared by
dissolving 5 g of 2,4,5-trinitro-9-fluorenone and 5 g of polycarbonate
(number average molecular weight of 30,000) into 50 g of tetrahydrofuran
was used instead in order to form a charge transporting layer. The
charging characteristic of the obtained photosensitive member was
evaluated in the same manner as those in Example 1, except that the member
was positively charged and no residual potential V.sub.r was measured.
The results were as follows; V.sub.O, +710 V; and E1/2, 2.50
lux.multidot.sec.
EXAMPLE 30
An electrophotographic photosensitive member was produced in the same
manner as those in Example 6, except that a solution prepared by
dissolving 5 g of 2,4,5-trinitro-9-fluorenone and 5 g of polycarbonate
(number average molecular weight of 30,000) into 50 g of tetrahydrofuran
was used instead in order to form a charge transporting layer. The
charging characteristic of the obtained photosensitive member was
evaluated in the same manner as those in Example 6, except that the member
was positively charged and that no residual potential V.sub.r was
measured.
The results were as follows: V.sub.O, 690 v; and E1/2, 2.67
lux.multidot.sec.
As understood from the above description, because the electrophotographic
photosensitive member employs specific polyvinyl acetals as a binder resin
in the photosensitive layer, it achieves good sensitivity, potential
stability and low residual potential in repeated use. Accordingly, an
electrophotographic apparatus, a device unit and a facsimile machine
employing such electrophotographic photosensitive member achieve
substantially the same advantages.
While the present invention has been described with reference to what are
presently considered to be the preferred embodiments, it is to be
understood that the invention is not limited to the disclosed embodiments.
To the contrary, the invention is intended to cover various modifications
and equivalent arrangements included within the spirit and scope of the
appended claims. The scope of the following claims is to be accorded the
broadest interpretation so as to encompass all such modifications and
equivalent structures and functions.
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